The present invention relates to a universal blow mold assembly having a mold carrier for receiving identical mold shells with different preform neck heights.
Typical universal mold assemblies for manufacturing plastic containers include two half mold carriers each adapted to carry one half of a mold shell. Each mold shell half is interchangeable with a corresponding mold carrier to allow for different shaped articles to be manufactured by the mold assembly. The mold assembly includes a pair of support arms each supporting a corresponding carrier. The support arms are connected to a pivot point and act as levers to rotate about the pivot point to open and close the mold halves carried by the support arms through the carriers. Various latching and locking mechanisms have been developed to hold the carriers together during the forming operation. To allow for proper alignment of the mold shell during closure of the mold half carriers, one mold half carrier parting wall usually has bushings which mate with pins extending from the parting wall of the other mold half carrier. Further, the mold shell typically has a recess into which a clamp from the mold carrier is received to hold the mold shell to the carrier.
The universality of the mold carrier, however, is limited to mold shells for containers having the same neck height. This is because the preform blown into the mold shell also carries the neck of the bottle that is normally positioned above the mold carrier. A blow nozzle in the molding equipment is inserted vertically downward a predetermined distance into the neck of the bottle. This predetermined distance is measured relative to the distance from the bottom of the mold assembly, up above the mold assembly to the top of the neck of the preform. While the vertical height of the mold carrier remains constant, the neck height of the bottle may change due to specific market requirements. That is a single bottle shape may have as many as six or more different neck heights each of which is specific to a market. Since the mold shell is secured to the mold carrier at, a predetermined vertical alignment, different mold shells need to be manufactured to locate the shape of the bottle relative to mold shell threaded apertures to accommodate the differing neck heights. Consequently, while the actual shape of the container does not change, different mold shells are required for different neck heights associated with a bottle configuration.
There is a need to develop a universal mold assembly that allows the same mold shell to be used in a mold carrier irrespective of the neck height of the bottle to be blow molded.
The present invention relates to a mold assembly having two mold half shells and corresponding mold half carriers. The assembly utilizes a novel intermediate interconnecting member preferably comprising a pair of ring shaped locating members. The locating members have an inner locating wall preferably in the form of a stepped shoulder that fits into a recessed slot in the outer wall of the mold shells. The locating members preferably further include an outer wall that fits into a recessed slot in the inner wall of the mold half carriers. The inner and outer locating walls of the locating members are vertically positioned relative to each to determine the vertical registry of the mold shell to the mold carrier.
By utilizing various different intermediate interconnecting members that differ by the relative vertical positioning of the inner and outer locating surfaces, universal mold shells and mold carriers may be used for containers having differing neck heights whereby the neck height adjustment is accommodated by changing the intermediate interconnecting member. As a consequence, quick changes in the assembly can be made by replacing a relatively less expensive interconnecting ring members for each preform neck finish height as compared to utilizing more expensive mold shells. The interconnecting ring members can be kept as part of standard parts for the mold carrier.
The present invention further contemplates utilizing a base insert located below the mold half shells having a base wall that defines the shape of the base of the container. The assembly further includes an interchangeable pedestal spacer plate positioned below the base insert having a thickness chosen relative to the vertical registry defined by the intermediate interconnecting member.
In accordance with one aspect of the present invention there is provided a mold assembly comprising two mold half shells having first inner walls defining a cavity whose shape corresponds to side walls of a container to be formed in the assembly. The mold half shells have a first outer wall. The assembly comprises two mold half carriers each releasably supporting a corresponding one of the mold half shells. The two mold half carriers are moveable between an open position allowing access to the mold half shells and a closed position for formation of a container within the cavity. The mold half carriers have a second inner wall corresponding to the first outer wall of the mold half shells when the mold half carrier supports the mold half shell. The assembly further includes an intermediate interconnecting member for securing in vertical registry each mold half shell with the corresponding mold half carrier. The intermediate interconnecting member comprises an outside connecting surface adapted to secure the intermediate interconnecting member to the second inner wall of the mold half carrier and comprises an inside connecting surface adapted to secure the intermediate interconnecting member to the first outer wall of the mold half shell. The inside and outside connecting surfaces of the intermediate interconnecting member are vertically spaced relative to each other to define vertical registry between the mold half shell and the corresponding mold half carrier.